Objective c 是否删除由NSRectFill完成的图形？

我有一个

NSBox

，在其中我用

NSRectFill（）

绘制小矩形。我的代码如下所示：

for (int i = 0; i <= 100; i++){


    int x = (rand() % 640) + 20;
    int y = (rand() % 315) + 196;

    array[i] = NSMakeRect(x, y, 4, 4);
    NSRectFill(array[i]);
}

---

for（int i=0；i听起来像是在drawRect之外绘制：。如果是这种情况，请将绘图代码移动到视图（框或某个子视图）中drawRect:method。否则，您的绘图将像您看到的那样被Cocoa绘图系统踩踏。您还需要使用计时器或动画，而不是循环来重复绘图。
我最近为试图对圆进行类似操作的人编写了一个示例程序。我采用的方法是创建一个cir数组cle规范，并在drawRect中绘制它们。它工作得很好。也许它会有帮助。如果你想要整个项目，你可以下载它

还值得注意的是，即使第二个
for
循环位于
drawRect:
中，
性能选择器：withObject:afterDelay:
消息意味着
executeFrame
消息在之后发送和接收（即在外部）
drawRect:
。向视图发送
display
消息是正确的解决方案，这是非常罕见的。通常，您只需设置其
needsDisplay
，让AppKit告诉它在正确的时间绘制，并在AppKit告诉它时绘制视图的所有图形，而在任何其他时间都不需要。
for (int i = 0; i <= 10; i++) {      

   [self performSelector:@selector(executeFrame) withObject:nil afterDelay:(.05*i)];   

    }

@implementation CircleView

@synthesize maxCircles, circleSize;

- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        maxCircles = 1000;
        circles = [[NSMutableArray alloc] initWithCapacity:maxCircles];
    }
    return self;
}

- (void)dealloc {
    [circles release];
    [super dealloc];
}

- (void)drawRect:(NSRect)dirtyRect {
    NSArray *myCircles;
    @synchronized(circles) {
        myCircles = [circles copy];
    }
    NSRect bounds = [self bounds];
    NSRect circleBounds;
    for (NSDictionary *circleSpecs in myCircles) {
        NSColor *color = [circleSpecs objectForKey:colorKey];
        float size = [[circleSpecs objectForKey:sizeKey] floatValue];
        NSPoint origin = NSPointFromString([circleSpecs objectForKey:originKey]);
        circleBounds.size.width = size * bounds.size.width;
        circleBounds.size.height = size * bounds.size.height;
        circleBounds.origin.x = origin.x * bounds.size.width - (circleBounds.size.width / 2);
        circleBounds.origin.y = origin.y * bounds.size.height - (circleBounds.size.height / 2);
        NSBezierPath *drawingPath = [NSBezierPath bezierPath];
        [color set];
        [drawingPath appendBezierPathWithOvalInRect:circleBounds];
        [drawingPath fill];
    }
    [myCircles release];
}

#pragma mark Public Methods

-(void)makeMoreCircles:(BOOL)flag {
    if (flag) {
        circleTimer = [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(makeACircle:) userInfo:nil repeats:YES];
    }
    else {
        [circleTimer invalidate];
    }
}

-(void)makeACircle:(NSTimer*)theTimer {
    // Calculate a random color
    NSColor *color;        
    color = [NSColor colorWithCalibratedRed:(arc4random() % 255) / 255.0
                                      green:(arc4random() % 255) / 255.0
                                       blue:(arc4random() % 255) / 255.0
                                      alpha:(arc4random() % 255) / 255.0];
    //Calculate a random origin from 0 to 1
    NSPoint origin;
    origin.x = (double)arc4random() / (double)0xFFFFFFFF;
    origin.y = (double)arc4random() / (double)0xFFFFFFFF;
    NSDictionary *circleSpecs = [NSDictionary dictionaryWithObjectsAndKeys:color, colorKey, 
                                 [NSNumber numberWithFloat:circleSize], sizeKey, 
                                 NSStringFromPoint(origin), originKey,
                                 nil];
    @synchronized(circles) {
        [circles addObject:circleSpecs];
        if ([circles count] > maxCircles) {
            [circles removeObjectsInRange:NSMakeRange(0, [circles count] - maxCircles)];
        }
    }
    [self setNeedsDisplay:YES];
}

@end